Enhancing systematic tolerance in Bermuda grass (Cynodon dactylon L.) through amplified alkB gene expression and bacterial-driven hydrocarbon degradation.

This study aimed to access the impact of soil polluted with petroleum (5, 10 g petroleum kg-1 soil) on Bermuda grass (Cynodon dactylon L.) with and without applied bacterial inoculants (Arthrobacter oxydans ITRH49 and Pseudomonas sp. MixRI75). Both soil and seed were given bacterial inoculation. The evaluated morphological parameters of Bermuda grass were fresh and dry weight. The results demonstrated that applied bacterial inoculants enhanced 5.4%, 20%, 28% and 6.4%, 21%, and 29% shoot and root fresh/dry weights in Bermuda grass under controlled environment. The biochemical analysis of shoot and root was affected deleteriously by the 10 g petroleum kg-1 soil pollution. Microbial inoculants enhanced the activities of enzymatic (catalase, peroxidase, glutathione reductase, ascorbate peroxidase, superoxide dismutase) and non-enzymatic (ɑ-tocopherols, proline, reduced glutathione, ascorbic acid) antioxidant to mitigate the toxic effects of ROS (H2O2) under hydrocarbon stressed condition. The maximum hydrocarbon degradation (75%) was recorded by Bermuda grass at 5 g petroleum kg-1 soil contamination. Moreover, bacterial persistence and alkane hydroxylase gene (alkB) abundance and expression were observed more in the root interior than in the rhizosphere and shoot interior of Bermuda grass. Subsequently, the microbe used a biological tool to propose that the application of plant growth-promoting bacteria would be the most favorable choice in petroleum hydrocarbon polluted soil to conquer the abiotic stress in plants and the effective removal of polyaromatic hydrocarbons in polluted soil.

Mycorrhized wheat and bean plants tolerate bismuth contaminated soil via improved metal detoxification and antioxidant defense systems.

Contamination of agricultural fields with bismuth (Bi) reduces crop yield and quality. Arbuscular mycorrhizal fungi (AMF) are known to enhance plant growth and crop production, even under stressful conditions such as soil contamination with heavy metals. The objective of this study was to investigate the effect of AMF on the mitigation of Bi-phytotoxicity in wheat (Triticum aestivum) and beans (Phaseolus vulgaris) and to provide a comprehensive evaluation of the physiological and biochemical basis for the growth and development of AMF-induced plants under Bi stress conditions. Wheat and bean were treated by Bi and AMF individually and in combination. Then the physiological and biochemical responses in the shoot and roots of the two crop species were studied. Evident retardations in plant growth and key photosynthesis-related parameters and accumulation of MDA, H2O2, as markers of oxidative stress, were observed in plants subjected to Bi. AMF colonization reduced the uptake and translocation of Bi in the plant organs by enhancing the exudation of polyphenols and organic acids into the rhizospheric soil. Mycorrhized wheat and bean plants were able to attenuate the effects of Bi by improving metal detoxification (phytochelatins, metallothionein, total glutathione, and glutathione-S-transferase activity) and antioxidant defense systems (both enzymatic and non-enzymatic) and maintaining C assimilation and nutrient status. The current results suggest the manipulation of AMF as a powerful approach to alleviate the phytotoxicity of Bi in legumes and grasses.